The invention relates to a suction roll comprising a roll shell rotatable on journals and which roll shell comprises a cylinder having a plurality of perforated sections. Suction is directed to the internal space of the roll shell and air is sucked through the perforations to press the paper web toward the outer surface of the roll shell and which roll shell has an interior space which is maintained at a low air pressure by an external suction pipe, the interior of the suction roll having no suction box or corresponding device arrangement, the result of which is that suction is directed only to holding the paper web on the outer surface of the roll shell.
An earlier patent application FI 881106 (equivalent U.S. Ser. No. 07/320,985, filed Mar. 9, 1989, applicant describes a suction roll construction in which the paper web is pressed toward a lower drying cylinder. The application is based on the idea of the paper web being supported by a suction roll which does not comprise a suction box inside the roll. In accordance with the above-mentioned invention, the suction roll construction has been formed in such a way that the suction roll comprises a cylinder having perforations, and a separate recess, preferably a groove, through which low air pressure is distributed over a larger area on the roll surface for achieving a suitable suction force on the paper web. By dimensioning the holes appropriately in accordance with this application, a sufficient force to hold the web to the roll surface can be achieved without having to place a suction box or another corresponding arrangement inside the suction roll.